1. Field of the Invention
The present invention relates to an "ultraviolet curing lamp device" for the curing of organic compound products and especially photopolymerizable materials. It is particularly directed to such a device which may be operated at temperatures lower than the conventional air cooled devices and, is capable of curing a broader spectrum of products, some of which could not maintain their integrity at higher curing temperatures. Further, it is directed to a device which is air cooled rather than water cooled.
2. Prior Art Statement
The use of ultraviolet lamps for curing various organic compound materials is well known. Thus, photopolymerizable inks and plastics are cured upon exposure to ultraviolet radiation.
U.S. Pat. No. 4.309,616 is directed to an apparatus for producing ultraviolet radiation for treatment of humans but operates in the radiation range of 315 nm to 400 nm. The patent describes heat absorbing and intercepting means including an auxiliary reflector in front of a radiation source as well as an air cooling means located behind an ultraviolet light source reflector. While this patent is directed to ultraviolet light radiation, it does not have the requisite output for curing photopolymerizable materials and is directed to tanning humans. Thus, the patent fails to teach any of the physical improvements embodied in the present device of the invention.
U.S. Pat. No. 4,298,806 describes an apparatus for ultraviolet curing and includes air cooling means as well as an ellipsoidal reflector. However, this patent utilizes a long, curved optical wave guide and a thin film filter of titanium dioxide. The wave guide is designed to be bent at an angle such that cool ultraviolet light, i.e., radiation, is emitted. The present invention eliminates the need for a wave guide and enables much higher powered outputs to be utilized at substantially lowered temperatures.
U.S. Pat. No. 4,274,028 is directed to an apparatus for generating ultraviolet light of high intensity without heat production but requires a complex anode/cathode arrangement as well as vacuum-producing equipment. This patent teaches a device which is very different from that of the present invention. Due to the four different air currents utilized in the device of the present invention, this type of prior art evacuation as well as other prior art techniques such as water cooling, is eliminated.
U.S. Pat. No. 4,101,424 is directed to an ultraviolet lamp device employing a water jacket and heat exchanger to effect cooling. Again, unlike the present invention, this prior art requires water circulation. It should be noted that the present invention does not include a water circulation system, and, to make a comparison, in general, water circulation systems require plumbing, more expensive hardware, pumping, filtering, de-ionizing, and may create the potential for hazard due to the combination of high voltage or current being utilized in the same device through which water passes. As mentioned, all of these problems are eliminated by the present invention device.
U.S. Pat. No. 4,055,769 teaches a method and apparatus for curing a coating on a substrate wherein an ultraviolet light source is used in conjunction with a reflector which includes two opposite quarter circular concave sections and two partial parabolic sections. In this patent, hot mirrors such as aluminum which is vaporized with quartz, are used and the very low temperatures at high outputs which are achieved with the present invention cannot be obtained with this prior art device. In fact, the invention described in this patent is directed to a very narrow band of ultraviolet light and could not successfully be employed with broad band curing such as is used in the present invention.
U.S. Pat. No. 4,048,490 describes an apparatus for delivering a relatively cold ultraviolet light to a substrate for ultraviolet curing. While this patent teaches the use of dichroic reflective surfaces, it should be noted that these surfaces are flat and do not have focal points and, more importantly, are described in conjunction with a system which requires water cooling to lower the temperature of operation. As mentioned above, the use of water cooling systems creates many undesirable features which the present invention eliminates.